Flight is a vital component of butterfly natural history, and flight-associated morphology is thought to be under strong selection for the performance of critical behaviors such as patrolling, courtship and oviposition. However, while different behaviors require different proportions of flapping versus gliding flight, few studies actually quantify butterfly flight behavior. Moreover, as butterfly flight is anteromotoric, no prior study has measured the role of hind wing allometry in flight. Using high-speed videography, this study compares the flight of two species of Haeterini (Nymphalidae) that regularly employ gliding flight. We also employ stereo videography and experimental hind wing area reduction to measure the effects of hind wing allometry on flight. Results suggest that although the forewings are reliable predictors of flight in these two species, relative hind wing area can significantly affect gliding flight performance, and should be considered as a factor in future investigations on flight-associated morphology in butterflies.